This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Nudaurelia capensis omega virus-like particle, a T=4 virus capsid, undergoes a pH promoted maturation process. Using the fully upgraded instrumentation on SSRL BL4-2 we have begun studying the kinetics of structural change associated with the maturation process. Performing manual mixing, followed by a series of time-resolved data acquisition (each 3 sec exposure), we have recently been able to isolate a structural intermediate at intermediary pH values between neutral (pH 7.6) and pH 5.0, which was used to promote the maturation in our earlier studies. We also observed that two VLPs with different RNA contents show slightly different shape and diameter. We have initiated the time-resolved studies of the entire process of maturation with a millisecond time-resolution in an attempt to examine our hypothesis that the repulsive electrostatic forces among the capsid subunits at the 3-fold and quasi 3-fold axies being the key triggering event in the maturation.